I recently bought a new mazda CX-7 AWD. After owning it just a few days I noticed the car had a shutter when I hit the brakes, it feels like a roter issue. The wheel and brake pedal seem to pulse back at me. Additonally, the entire exhaust system is black and rusty. Any help, opinions, reasons for these issues...My car is a 08, however, it was produced in September of 07.....Please help! -a very confused mazda owner!